This invention relates to cameras for daylight and flash photography, and, more particularly, to a switch device for selection of the operating range and for flash energy supply control in such camera especially of the type having an electronic flash unit either incorporated therein or removably attached thereto.
It is known to provide a camera for daylight and flash photography with a mode selector operating upon detection of occurrence of a lower light value beyond an automatically operating daylight exposure range to automatically switch the camera to an automatically operating flash exposure range in which the diaphragm aperture is adjusted in accordance with the camera-to-object distance and the guide number value corresponding to the flash tube, such as, for example, disclosed in U.S. Pat. No. 3,073,226.
With this camera equipped with a flash unit of known construction, however, it is impossible to assure firing of the flash unit at a point in time such that a camera release is actuated. This is so because it takes a considerably long time to charge the storage capacitor from zero volts to a satisfactory operating voltage level for the speedlight. It has, therefore, been the prior art practice at first to view the exposure meter of the camera indicating whether or not the light value is in a daylight exposure range, and then, if flash lighting is necessary, to close a flash energy supply control switch manually prior to the actuation of camera release. When the light value is marginally available or unavailable in the daylight exposure range, the manual switching of the camera by seeking the condition of the exposure meter for each actuation of camera release is a very time consuming operation. Further, should a necessary manipulation be overlooked for maintaining of the flash energy supply control switch closed, the storage capacitor will unnecessarily be connected to the battery. As a result, the battery may run down by leakage and the like after a relatively short period of useful operation. This becomes serious particularly when the camera is not used for a long time.
Accordingly, the present invention has for its general object to provide a camera for daylight and flash photography adapted to operate with an electronic flash unit and which overcomes the above-mentioned conventional drawbacks.
In one embodiment of the invention, a mechanism for jointly actuating and jointly releasing a flash mode selector and a flash energy supply control switch mounted in the camera housing comprises actuating means for controlling opening and closing operation of the selector and the switch, first switch blocking means arranged between the actuating means and a shutter release trigger upon actuation of the trigger employing a stroke length greater than normal to be moved out of the path of movement of the actuating means so that the flash mode is selected and the switch is closed, second switch blocking means associated with setting means, the latter being manually operable from the outside of the camera housing, and rendering operative the actuating means, and blocking means responsive to occurrence of a lower light value beyond an automatically operating daylight exposure range for preventing the shutter from being caused to run by a first actuation of the shutter release trigger.
By this mechanism it is made possible after the positive setting of the preparatory means, if flash lighting is necessary, to automatically switch the camera from the daylight to the flash exposure range with simultaneous closure of the flash energy supply control switch in response to a first actuation of the shutter release trigger. Upon a subsequent second actuation of the trigger, a camera release starts to effect automatic formation of the flash exposure diaphragm aperture which is then followed by the running of the shutter. Alternatively, when the light value falls within the automatic daylight exposure range, the first actuation of the shutter release trigger results in the camera release, while the storage capacitor for the flash tube remains disconnected from the electrical power source despite the positive setting of the setting means. Thus, the electrical energy of the power source is not unnecessarily consumed. In addition thereto, when the setting means is set in the retracted position for the purpose of leaving the camera unused, the second switch blocking means is rendered effective so that even when the shutter release trigger is unintentionally depressed, the flash energy supply control switch is not closed. This further minimizes the possibility of unnecessary consumption of the electrical energy of the battery.